Hypersonic missiles now being designed and developed for use in the next decade will reach speeds that cause surface temperatures on the cylindrical shell structure to reach up to 3000.degree. F. for periods of 1 to 10 seconds. Trade studies have usually shown graphite composite structure to be the most weight efficient and cost effective when compared to metal structure. The highest temperature graphite composites using polyimide or PBI resin systems show useful strength for short periods (10 to 30 sec) up to 800.degree. F. or 1000.degree. F. These temperatures cannot be exceeded, therefore insulation is required, adding dead weight and cost.
For theses short exposures to high temperature an ablative surface insulation has usually been found most efficient in controlling surface temperature at the structural interface. Silicone rubber or phenolic-silica have most commonly been used to date. The phenolic-silica was found to be most effective for lowest weight. However, it must be formed at high pressure and temperature and is, therefore, usually made in segments (tiles) and bonded to the surface of the structure with low modulus adhesive. Neither system contributes any appreciable strength or stiffness to the basic structure. In may cases the insulation weight is comparable to the weight of the structural shell. The extra manufacturing steps are costly and time-consuming. Ablation often occurs in a non-uniform manner, degrading aero performance and results in more non-uniform heat transfer.